Refined ChDHFR-TS dimers have a non-crystallographic 51 axis
(O’Neil et al. 2003). By analyzing the cross-rotation peak list, CRANS was
able to identify the five correct dimer orientations. (Left) A
portion of the unit cell containing the 51 screw axis of ChDHFR-TS.
The dimerization axis of Dimer 3 is coincident with a crystallographic 2-fold.
Dimers x and x' are related by a crystallographic 2-fold. The
crystallographic a and c unit cell edges are shown for reference.
(Right) Top-down view showing the 5-fold symmetry.